Acidified biochar improves lead tolerance and enhances morphological and biochemical attributes of mint in saline soil

Abstract Lead (Pb) toxicity is a significant environmental issue, especially in areas with a past of industrial activities and mining. The existence of Pb in the soil can have negative impacts on plant growth and development, and it can also pose a risk to human health through the food chain. Acidified carbon has shown promise as an effective management technology for mitigating Pb toxicity. This study provides important insights into the potential of acidified biochar as a low-cost and eco-friendly method for managing Pb-contaminated soils. The current study explores the effectiveness of acidified biochar (AB) in alleviating Pb stress in mint. The study involved two levels of Pb (0 = control and 200 mg/kg Pb) and four levels of AB as treatments (0, 0.45, 0.90, and 1.20%). Results indicate that 1.20% AB was the most effective treatment, significantly decreasing root and shoot Pb concentration while enhancing shoot and root fresh and dry weight, shoot and root length, and shoot and root N, P, and K concentration. Moreover, a significant decrease in MDA (0.45AB, 0.90AB, and 1.20AB caused a decline in MDA content by 14.3%, 27.8%, and 40.2%, respectively) and an increase in ascorbic acid (0.45AB, 0.90AB, and 1.20AB led to an increase in ascorbic acid content of 1.9%, 24.8%, and 28.4%, respectively) validated the effectiveness of 1.20% AB compared to the control. Adding 0.45AB, 0.90AB, and 1.20AB led to an increase in soluble sugar content of 15.6%, 27.5%, and 32.1%, respectively, compared to the treatment without AB. Further investigations at the field level are suggested to confirm the efficacy of 1.20% AB as the best treatment against Pb toxicity in saline soil conditions.